【作者】 王文静；

【导师】 齐晓勇；

【作者基本信息】 河北医科大学 ， 内科学， 2011， 硕士

【摘要】 慢性心力衰竭(chronic heart failure,CHF)是多种心血管疾病的终末状态,高居心血管疾病死亡原因之首,其机制主要包括细胞凋亡、神经-体液因素和心室重构。近年来,慢性心力衰竭的药物治疗取得了巨大的进展,但仍有许多重症心力衰竭患者的药物治疗效果不佳。人们在倡导药物治疗的同时,也在积极寻求各种非药物治疗方法。心室再同步化治疗(cardiac resynchronization therapy,CRT)可改善CHF的症状,但适应证有限。目前,一种全新的心脏收缩调节(cardiac contractility modulation,CCM)方法,即通过心肌绝对不应期电刺激(absolute refractory period electrical stimulation ,ARPES)增强心肌收缩功能的方法引起了人们的关注。国内外研究表明,短时间CCM可明显增强正常心肌以及慢性心力衰竭心肌的收缩力,改善心功能及电生理稳定性,有改善长期预后的可能。但是,目前上述研究多停留于小型动物离体心脏研究及小样本临床研究,尚无大规模的临床试验,长期ARPES的有效性及安全性也待进一步证实。目的:本研究通过升主动脉根部套扎法建立兔慢性心力衰竭模型,给予绝对不应期电刺激,采用无创心脏超声以及血液学检查,观察绝对不应期电刺激对心功能及血浆BNP浓度的影响,探讨ARPES改善心力衰竭患者心功能及预后的机制,为临床治疗提供理论依据。方法:选用6月龄新西兰大白兔24只为实验对象,体重2.5～3.5kg,雌雄不拘,由河北医科大学动物实验中心提供。1.制备压力负荷过重慢性心力衰竭模型:实验动物麻醉后开胸,充分暴露心脏,于升主动脉根部远端1.0cm处缩窄升主动脉外径至原外径的60%,关闭胸腔,抗生素抗感染治疗。2.检验慢性心力衰竭模型:造模后第4周末、第5周末行心脏彩超检查,所有测量结果均取连续3次测量的平均值。造模成功判定标准为LVEF<40%。3.实验动物分组:造模后第4周末行心脏超声检查,将符合造模成功标准的动物模型随机分为对照组(n=5)、短期刺激组(n=6)及长期刺激组(n=6)。4.心脏绝对不应期电刺激:(1)长期刺激组:心力衰竭兔开胸放置电极并固定后发放CCM刺激(2ms,10V),延迟为30 ms。每天于固定时间连续刺激3小时,连续7天。(2)短期刺激组:放置电极,一次性连续刺激12小时。(3)对照组:放置电极,但不行电刺激。5.于第4周末、第5周末分别行心脏超声检查,测量左室射血分数(LVEF)、左室缩短分数(FS)、室间隔(IVS)、左室后壁厚度(LVPW)、左室舒张末内径(LVDSD)、左室收缩末内径(LVESD)。6.于第4周末、第5周末分别耳缘静脉采血5ml,采用ABC-ELISA法测定血浆BNP浓度。结果:1.模型制作:共对新西兰大白兔24只进行压力负荷过重慢性心力衰竭模型制备。术后即刻存活21只,术后四周末存活19只。根据心脏彩超结果及造模成功判定标准(LVEF<40%),共有17只造模成功。随机分为对照组5只,短期刺激组6只,长期刺激组6只。绝对不应期电刺激第5天,长期刺激组死亡1只,死亡原因为麻醉意外。2.入组动物一般情况:各组动物雌雄、月龄、体重、胆固醇、极低密度脂蛋白比较无统计学差异(P>0.05)。3.心脏彩超结果:第5周末,对照组、短期刺激组无统计学差异(P>0.05),长期刺激组各组数据均优于对照组和短期刺激组,有统计学差异(P<0.05)。4. BNP结果:第5周末,长期刺激组、短期刺激组BNP水平均低于对照组,有统计学差异(P<0.05)。长期刺激组BNP水平下降程度高于短期刺激组,两组间比较有统计学差异(P<0.05)。结论:1.升主动脉根部套扎法可成功建立兔压力负荷过重慢性心力衰竭模型。2.短期绝对不应期电刺激可降低血浆BNP水平,但不能改善心功能、抑制心室重构。3.长期绝对不应期电刺激可降低血浆BNP水平,增加心肌收缩力,改善心功能,抑制心室重构。更多还原

【Abstract】 Chronic heart failure (CHF) is a terminal state of a variety of cardio- vascular diseases, which is in the top of the causes of cardiovascular death. The mechanism of CHF includes apoptosis, nerve-humoral factors and left ventricular remodeling. In recent years, drug treatment of chronic heart failure has made tremendous progress, but there are still many patients with severe heart failure are ineffective through drug therapy. So people are actively seeking non-drug therapies. Cardiac resynchronization therapy (CRT) can improve symptoms of CHF, but the indication is limited. Currently, a new method called cardiac contractility modulation(CCM) has drawed people’s attention, which can enhance myocardial contractile function through electric stimulations applied during absolute refractory period (ARPES).Domestic and international research shows that short-term CCM can significantly enhance the myocardial contractility of nomal or chronic heart failure people, improve cardiac function and electrophysiological stability, and it is also likely to improve long-term prognosis. However, the current study stays in the isolated heart of small animals and small-scale clinical trials, there are no large-scale clinical trials, and the effectiveness and safety of long-term ARPES can be further confirmed.Objective: In this study, animal models of chroic heart failure were made by ligating ascending aortic root of rabbits. Then the absolute refractory period electrical stimulations were given, using non-invasive ultrasonic cardiogram and blood tests to observe the effects of cardiac function and plasma BNP concentration with ARPES. Our study would explore the mechanisms of ARPES improving cardiac function and prognosis of patients with heart failure, and provide a theoretical basis for clinical treatment. Methods: Twenty-four male or female New Zealand white rabbits were selected. They were purchased from the Test Animal Center of Hebei Medical University, aged about 6 months, weighted from 2.5kg to 3.5 kg.1. Made animal models of chronic heart failure for pressure overload: opened the chest of anesthetized animals, fully exposed the heart, ligated the ascending aortic from the distally of its root about 1.0 cm, making sure the diameter of the ascending aortic at the constriction to 60% of the original diameter, closed chest, injected antibiotics to avoid infection.2. Tested animal models of chronic heart failure: 4 weeks and 5 weeks after modeling, used ultrasonic cardiogram examining the rabbits. All measurements were taken the average of 3 consecutive measurements. Criteria for successful of modeling is LVEF<40%.3. Assigned animal groups: At the 4th weekends after modeling took examination of ultrasonic cardiogram, models consistent with the standard of successful modeling were randomly assigned to control group(n=5), short-term stimulation group(n=6) and long-term stimulation group(n=6).4. Applied ARPES:(1) long-term stimulation group: opened the chest of rabbits of heart failure, put in and fixed the electrodes, applied CCM stimulation(2ms, 10V), delay of 30 ms. The stimulations were applied at the same time in a day, continuing 3hours everyday for 7days.(2) short-term stimulation group: put in the electrodes, applied stimula- tions only once continuing 12 hours.(3) control group: the rabbits were also put in the electrodes, but there was no stimulations on them.5. At the end of 4th and 5th week, ultrasonic cardiogram were performed to measure left ventricular ejection fraction(LVEF)、fractional shortening(FS)、interventricular septal(IVS)、left ventricular posterior wall(LVPW)、left ventricular end diastolic diameter(LVEDD)、left ventricular end systolic diameter(LVESD).6. At the end of 4th and 5th week, collected peripheral blood 5ml, using for test plasma BNP concentration with ABC-ELISA method.Results:1. Model making: A total of 24 New Zealand white rabbits were made into chronic heart failure models by pressure overload. After the operation, immediately survived 21, 19 survived after 4 weeks. According to the results of echocardiography and the standard of successful model(LVEF<40%), a total of 17 were chosen. These 17 rabbits were randomly assigned to control group(n=5), short-term stimulation group(n=6) and long-term stimulation group(n=6). At 5th days of applying electrical stimulation, one of the rabbits from long-term stimulation group was dead, the cause of death was estimated to be of anesthesia.2. The general status of animals: There was no statistical difference among the three groups of experimental animals in general data, including gender, months, weight, cholesterol and very low density lipoprotein(VLDL) (P>0.05).3. The results of ultrasonic cardiogram: At the end of 5th week, there was no statistical difference between control group and short-term stimulation group (P>0.05), the data of long-term stimulation group was superior to control group and short-term stimulation group, there was statistical difference among them(P<0.05).4. The results of BNP: At the end of 5th week, BNP of long-term stimulation group and short-term stimulation group were lower than control group, there was statistical difference among them(P<0.05). BNP levels of decreasing in long-term stimulation group is higher than that in short-term stimulation group, there was statistical difference between the two groups(P<0.05).Conclusions:1. The chronic heart failure model causing by pressure overload could be established successfully by means of ligating the root of ascending aortic of rabbits.2. Short-term ARPES can decrease plasma BNP levels, but can not improve cardiac function and inhibit ventricular remodeling.3. Long-term ARPES can decrease plasma BNP levels, enhance myocardial contractility, improve cardiac function, and inhibit ventricular remodeling.更多还原